Thermionic tube



Oct 1929- a. JOBST 1,732,050

'I'HERMIONIC TUBE Filqfl Feb. 8, 1927 INVENTOR UNTl/f/f Jaur AT RNEY Patented Oct. 15, 1929 UNITED STATES PATENT OFFICE enNTHER JOBST, or BERLIN, GERMANY, ASSIGNOR T0 GESELLSCHAFT EfiR DRAHT- rosE TELEGRAPHIE M. B. 11., 0E BERLIN, GERMANY, A coRroRArToN or GERMANY THERMIONIC TUBE Application filed February 8,1927, SerialNo. 166,639, and in Germany February 23, 1926.

The present invention relates to a novel form of construction of electronic or thermionic tubes which can be used in any of the well. known and new circuit arrangements for rectification, amplification, and. wave generation purposes. The thermionic tube according to the invention comprises a cathode or filame'nt,'an anode or plate, and an auxiliary electrode which is interposed between filament and plate. The auxiliary electrode which is employed for the control of the current flowing across the said electrode, was heretofore so designed that the electrons issuing from the cathode or filament were enabled to strike the plate in relatively large numbers. The auxiliary electrode in accordance with this invention is so constructed that hardly any primary electrons are able to reach the plate, indeed, the plate can be struck only by secondary electrons that are emitted from the said auxiliary electrode. Electrons which issue from the filament, for instance a filament of the heated kind, consequently are caused to fall upon the said auxiliary electrode where they release secondary electrons, with the result that the space between the auxiliary electrode and plate is traversed wholly or nearly so by secondary electrons. As compared with the thermionic tubes of the conventional type, a tube of the type herein disclosed as distinguished therefrom by the advantage. that its characteristic is steeper, and that its operation as regards heating energy is more economical.

In the accompanying drawings, Figure 1 is a diagrammatic plan View of a section of my improved tube,

Figure 2 shows my improved tube in a circuit adapted for wave generation and,

Figure 3 shows my improved tube in another circuit arrangement.

According to the invention, as will be seen, the auxiliary electrode which is mounted between the heated filament and the plate must be so designed and disposed that the projection of the auxiliary electrode from the filament upon the plate must cover almost the entire plate, in other words, so that the plate is hidden when viewed from the filament.

One form of construction of such an auxiliary electrode consists in the Venetian-blindlike disposition of the constituent grid rods or sheet strips as illustrated in section in Figure 1 of the accompanying drawings, where K is the filament, A is the cylindrical anode or plate and G is the grid electrode. As can be'secn from that figure no electrons are able to find their way to the plate, indeed, they will be caused to impact upon the grid electrode.

In Figure 2 is shown a circuit arrangement adapted for wave generation, and includes the use of such a thermionic tube. According to' this circuit arrangement, plate A is united with the filament K through an oscillation circuit S, and there is further a connection between the grid G and the filament K by way of a resistance R. Across the terminals of the said resistance are set up potentials which cause control of the current flowing through the discharge vessel at the proper phase relationship, so that the maximum of the current of secondary electrons in the space between grid and plate will coincide with the minimum of potential, with the result that a negative resistance is created which allows of the generation of oscillations. I, in Figure 2 denotes the entire current of secondary electrons, and I, the current of primary electrons, and since in this form of construction the secondary-electron current predominates over the flow of primary electrons, it follows that the direction of the current flowing across the resist" ance, is opposed to the direction of flow of current in the grid circuit of an electron tube whichdoes not embody the features of the" present invention. It is also for this reason that such a circuit arrangement is possible only with a thermionic tube according to the present invention since in a tube presenting a high inverse amplification factor as heretofore used, owing to the prevalence of pri mary electron current in the grid circuit the potential across the resistance would be opposed in its phasef In Figure 3, a circuit arrangement is shown which, while apparently corresponding to the well known three-point connection is I difierent, as regards the physical phenomena attendant upon oscillation generation, from what it is in connection with the use of the I kind of tube customary heretofore, since also in this case, by virtue of the negative resistance between grid electrode and plate created by the secondary electrons, wave generation is made possib Having thus described my invention, what I claimis:

1. A thermionic tube, comprising a filament, an anode, and an auxiliary electrode, said auxiliary electrode consisting of a plurality of flat overlapping vanes, each vane being in a different plane, t e overlap being great enou h to shield the anode from any electronic ow from the filament.

2. A thermionic tube, including a filament, an anode, and an auxiliary electrode, said auxiliary electrode consisting of a plurality of overlapping vanes, each vane being in a difiere'nt plane, the overlap being great enough to shield the anode from any electronic flow from the filament.

.GUNTHER 'JOBST. 

